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Appendix VI.

1167

oil sprayer and working the oil pump by hand, the engine crank
is barred round till just over top dead centre. The lever D is
then pulled over to DX which connects the starting valve and its
cam. The reservoir H is next opened, and compressed air
admitted to the cylinder by pipe F through valve v. The engine
now rotates as an air engine. After five or six strokes, d is re

VQL.UM 6

placed in the vertical position, and the engine continues its course
as an oil engine. Fig. 1030 shews the starting card, which clearly
proves the regularity with which the engine takes its load on the
oil charge. When in working order the valve v serves as a
suction for the air pump, admitting thereto when the engine
piston is near the end of the compression stroke. The pressure is
further augmented to 750 Ibs. per sq. in. before delivery to the
reservoir j.

The comparison of the Diesel compression with that in steam
and gas engines is made In Fig. 1030 for equal volumes of
cylinder. It is this excessive compression which is without doubt
the main factor in the high efficiency obtained, but the all-over